Arrhythmias (II)
What does this tracing show?
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Answer: Accelerated AV junctional rhythm with 1:1 retrograde conduction to atria
Discussion
This patient has a regular rhythm of 70 bpm. The QRS complexes are narrow, indicating that they originated from above the ventricle. There is no P wave in front of the QRS. However, there is a negative deflection immediately following the QRS, which is especially noticeable in the inferior leads, indicating retrograde activation of the atria.
This tracing is a good example of AV junctional rhythm with 1:1 conduction to the atria. Because the rate is not faster than 130 bpm, it is not junctional tachycardia. However, because the rate is faster than the intrinsic AV junctional rate of 40-50 bpm, this rhythm is termed accelerated junctional rhythm. Accelerated junctional rhythm is due to either digitalis toxicity, myocardial ischemia or infarction, or an excess amount of catecholamines circulating.
The mean QRS axis is shifted to the left, reflecting left anterior fascicular block, and the QRS voltage is increased suggesting left ventricular hypertrophy (LVH). The QS pattern in V1 and V2 may be due to LVH with or without old anteroseptal myocardial infarction.
What does this tracing show?
Sinus rhythm with 1° atrioventricular (AV) block
Accelerated AV junctional rhythm with 1:1 retrograde conduction to atria
Accelerated idioventricular rhythm with 1:1 retrograde conduction to atria
View the correct answer
Answer: Accelerated AV junctional rhythm with 1:1 retrograde conduction to atria
Discussion
This patient has a regular rhythm of 70 bpm. The QRS complexes are narrow, indicating that they originated from above the ventricle. There is no P wave in front of the QRS. However, there is a negative deflection immediately following the QRS, which is especially noticeable in the inferior leads, indicating retrograde activation of the atria.
This tracing is a good example of AV junctional rhythm with 1:1 conduction to the atria. Because the rate is not faster than 130 bpm, it is not junctional tachycardia. However, because the rate is faster than the intrinsic AV junctional rate of 40-50 bpm, this rhythm is termed accelerated junctional rhythm. Accelerated junctional rhythm is due to either digitalis toxicity, myocardial ischemia or infarction, or an excess amount of catecholamines circulating.
The mean QRS axis is shifted to the left, reflecting left anterior fascicular block, and the QRS voltage is increased suggesting left ventricular hypertrophy (LVH). The QS pattern in V1 and V2 may be due to LVH with or without old anteroseptal myocardial infarction.